Crosslinked electrospun composite membranes of poly(vinyl alcohol) and poly(vinyl chloride): tunable mechanical properties, porosity and performance

Managing water resources has become one of the most pressing concerns of scientists in both academia and industry. Broadening access to nontraditional water feedstocks, such as brackish water, seawater and wastewater, requires a robust pretreatment process to prolong the lifetime and improve the efficiency of reverse osmosis treatment processes. Herein, pretreatment membranes with tunable hydrophilic characteristics and mechanical properties were developed through a facile and scalable technique. Specifically, poly(vinyl alcohol) (PVA) and poly(vinyl chloride) (PVC) were electrospun at various PVA-to-PVC mass ratios and then crosslinked with a poly(ethylene glycol) diacid. Fiber diameters and morphologies were characterized using scanning electron microscopy (SEM); Fourier transform infrared spectroscopy and confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately determine the relative concentrations of the two polymers on the co-spun mat. The crosslinking reaction noted above tuned the membrane porosity from 500 to 80 nm, as seen using SEM, and the mechanical properties were probed using tensile testing. The data revealed that the PVC content controlled the mechanical strength; moreover, higher PVA contents were expected to increase water permeation by enhancing the hydrophilicity, but the higher degree of crosslinking in these materials actually reduced water permeation. This work introduces a facile, scalable route for the manufacture of pretreatment membranes with tunable porosity, mechanical properties and water permeation behavior.